Measurement of cough effectiveness in patients with cough or retained secretions as a major symptom is clinically useful. This can be approximated by measurement of peak changes in intrapleural pressure during cough. A known technique for measuring intrapleural pressure utilizes an esophageal balloon catheter. While the esophageal balloon catheter serves its intended purpose, it requires placement in the subjects respiratory tract by insertion through the mouth, and thus constitutes an invasive technique. It will be readily apparent that such an invasive technique is not suited for long term or serial monitoring, which is often desirable in the case of patients with cough or retained secretions. It is therefore desirable to provide a non-invasive technique for semiquantitatively measuring intrapleural pressure during a cough.